Serum taken from a patient being treated with lithium for
manic-depressive illness was analyzed for lithium concentration. a
reading of 212 units was obtained for the intensity of the 671 nm
red emission line. then 1.00 ml of a 11.2 mm lithium standard was
added to 9.00 ml of serum, and this spiked serum gave an intensity
reading of 546 units. what is the original concentration of li in
the serum?

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.